Pitavastatin calcium is chemically known as (3R,5S)-7-[2-cyclopropyl-4-(4-fluorophenyl)quinolin-3-yl]-3,5-dihydroxy-6(E)-heptenoic acid calcium salt having the formula IA is known in the literature.

Pitavastatin is a synthetic lipid-lowering agent that acts as an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme a (HMG-CoA) reductase (HMG-CoA Reductase inhibitor). This enzyme catalyzes the conversions of HMG-CoA to mevalonate, inhibitors are commonly referred to as “statins”. Statins are therapeutically effective drugs used for reducing low density lipoprotein (LDL) particle concentration in the blood stream of patients at risk for cardiovascular disease. Pitavastatin is used in the treatment of hyperchloesterolemia and mixed dyslipidemia.
Pitavastatin calcium has recently been developed as a new chemically synthesized and powerful statin by Kowa Company Ltd, Japan. On the basis of reported data, the potency of Pitavastatin is dose-dependent and appears to be equivalent to that of Atorvastatin. This new statin is safe and well tolerated in the treatment of patients with hypercholesterolaemia. Significant interactions with a number of other commonly used drugs can be considered to be extremely low.
Processes for the preparation of Pitavastatin are described in EP-A-0304063 and EP-A-1099694 and in the publications by N. Miyachi et al. in Tetrahedron Letters (1993) vol. 34, pages 8267-8270 and by K. Takahashi et al. in Bull. Chem. Soc. Japan (1995) Vol. 68, 2649-2656. These publications describe the synthesis of Pitavastatin in great detail but do not describe the hemi-calcium salt of Pitavastatin. The publications by LA. Sorbera et al. in Drugs of the Future (1998) vol. 23, pages 847-859 and by M. Suzuki at al. in Bioorganic & Medicinal Chemistry Letters (1999) vol. 9, pages 2977-2982 describe Pitavastatin calcium, however, a precise procedure for its preparation is not given. A full synthetic procedure for the preparation of Pitavastatin calcium is described in EP-A-0520406. In the process described in this patent Pitavastatin calcium is obtained by precipitation from an aqueous solution as a white crystalline material with a melting point of 190-192° C.
US20090182008 A1 discloses polymorphic form A, B, C, D, E, and F, and the amorphous form of Pitavastatin Calcium salt (2:1). In particular, crystalline Form A having water content from about 5% to about 15% and process for its preparation are disclosed.
US20090176987 A1 also discloses polymorphic form crystal form A of Pitavastatin Calcium which contains from 5 to 15% of water and which shows, in its X-ray powder diffraction as measured by using CuKα radiation, a peak having a relative intensity of more than 25% at a diffraction angle (2θ) of 30.16°.
WO2007/132482 A1 discloses a novel process for the preparation of Pitavastatin Calcium by condensing bromide salt of formula-3 with aldehyde compound of formula-4 to obtain olefinic compound of formula-5 and converting olefinic compound to Pitavastatin Calcium via organic amine salt for purification.
There are no reports available in the prior art for the preparation of Pitavastatin Magnesium. Thus, the inventors of the present inventions provide a novel pharmaceutically acceptable salt of Pitavastatin, preferably magnesium salt.